Originally the compasses were tools of the Ess?nce Lords. One of the Original Navigators, S?zur Vranuk, found some compasses while exploring. A certain member of the Loremasters at the time was willing to teach him how to use the device.
There appear to be a limited number of the devices and require extensive training to use.
The certain Loremaster is Andraax
seems I have to disagree with these numbers.
For me the number of Navigators is somewhere at least 10 000, and maybe more.
Let me explain how I get that idea.
There's going to be a few spoilers about the working of the Navigators and some informations some GM might want to keep unknown to their players below...
- First, the Navigators have a whole continent as center of operation : Ixyia. ( Check SWMA4, P98 for the details )
- Second there's several regular shipping lines around Emer and Jaiman, most of theses shipping lines require the help of a Navigator ( or an apprentice ) on at least one ship in a convoy for a safe travel.
- Third there's regular communications between Emer and Jaiman, through Eidolon, Lethys and Norek, here also, the help of a Navigator is more than welcome.
- Fourth, there's all the places and locations barely described in the Master Atlas ( Gethrya, the Jan, Kerovan States, Jhoridia, Xa'iayn, Vashaan Domains, Laakia [Raven Queen], Yuar Noak, Khajir Goak, Torakh Gul, Abarquan Islands, Dalov Dom, ... Basically all the TL3+ places with mixed economy ) that do trade... and to be able to trade, they need to be able to import and export goods... for that they need reliable trade routes.. Only the Navigators provide something reliable.
-Fifth, Jumping is just ruffles and flourishes... most of the Navigators are hired to go from location A to location B overland or on a ship. Just a tiny fraction of the requests are for a jump.
- Sixth We can expect that at least 100 or 200 ships leave harbour on a daily basis... so that means that every day the Navigators needs to provide about 200 Navigators to fill in the requests. Yes, about the same number of ships should hit the harbour each day too... but.... you have to remember, the request can come early in the morning while the ship with the Navigator will only hit harbour in the evening... so you need two Navigators... because the tide won't wait for the second ship.
I could probably find some other reasons, but these are the ones that pop out of my brain when I start thinking about it.